Mixed aluminum soap compositions



United States Patent i 2,887,457 MIXED ALUMINUM SOAP COMPOSITIONS Joseph Cunder, East Orange, and Francis J. Licata, West Caldwell, N.J., assignors to Nopco Chemical Company, Harrison, NJ., a corporation of New Jersey No Drawing Application December 6, 1955 Serial N0. 551,203

V 8 Claims. (Cl. 260-17) This invention relates to novel aluminum soap com positions. More particularly, it relates to novel aluminum soap compositions which are highly suited for use as flatting agents in paint, lacquer and varnish formulations.

It is well known in the art that a flatting agent when added to a glossy coating will reduce the luster of that coating and produce a fiat appearance. Flatting agents when ground into a vehicle, cause the incident light to be reflected from a deposited film in a diffuse rather than specular fashion.

The properties and characteristics which determine whether or not a particular composition can be employed successfully as a flatting agent are many and diverse. The solubility of a composition proposed for use as a flatting agent is one of the most important considerations. In order to function effectively as a flatting agent, the composition employed must be insoluble in the vehicle in which it is to be ground so that maximum flatting per unit of weight will be secured. However, other characteristics of the product are also important. Thus, in addition to being insoluble in the solvent vehicle, the composition proposed for use as a flatting agent must be such that it can be readily ground in the vehicle to a desired particle size. Furthermore, to be satisfactory as a flatting agent a composition must have a refractive index which is relatively close to that of the vehicle in which it is to be ground so that its presence in the body of the film produced therefrom will not be apparent.

Certain metallic soaps have been employed heretofore as flatting agents in paint, varnish and lacquer formulations. Aluminum stearate, calcium stearate and zinc stearate are the metallic soaps which have been employed most often for this purpose. However, to a certain extent, the utility of these compositions for use as flatting agents is restricted by their unique characteristics. Thus, for example, the physical characteristics of metallic soaps are such that undue thickening occurs when high concentrations thereof are ground into the vehicle. Thickening of the vehicle, ofcourse, is undesirable. It renders the smooth and even application of the coating composition to a surface extremely diflicult. In order to avoid thickening, metallic soaps are used generally in relatively low concentrations. However, the presence of a low concen tration of metallic soap in the vehicle leaves much tobe desired since it often results in the production of thin films whose weathering characteristics are not always adequate. However, the use of relatively low concentrations of metallic soaps does not, in all instances, obviate the danger of undue thickening. Certain metallic soaps, even at relatively low concentrations, form gels with the vehicle at elevated temperatures. Thus, when employed in a paint, varnish or lacquer formulation as a flatting agent, a metallic soap composition is ground into the solvent vehicle. Temperatures, sufliciently high to induce the formation of a gel, are developed in the grinding mill during the grinding operation. Accordingly, the metallic soap chosen for use must be one which will not form a gel with the vehicle at the temperatures developed during 2,887,457 Patented May 19, v1959 The object of this invention is to provide novel alu minum soap compositions for use as flatting agents in the formulation of paints, lacquers and varnishes.

A more particular object of the invention is to provide flatting agents ofthe aluminum soap type which are especially suited for use in the formulation of lacquers.

A further object of the invention is to provide aluminum soap compositions which, in addition to having excellent flatting characteristics and properties, possess outstanding temperature stability qualities.

Other objects of the invention will be obvious and will, in part, appear hereinafter.

It has been discovered that certain aluminum soap compositions are excellent flatting agents having outstanding temperature stability characteristics. The novel products of this invention are multiple aluminum soap compositions, the organic acid portion of which comprises a mixture of a polyacrylic acid and a saturated fatty acid of a type to be designated hereinafter. These aluminum soap compositions are precipitated from an aqueous solution having dissolved therein water-soluble soaps of saturated aliphatic monocarboxylic acids having a carbon chain length of from about 16 to about 22 carbon atoms and water-soluble salts of polyacrylic acids. The expression fmultiple aluminum soap compositions" will be used throughout the specification and in the claims to distinguish the novel products of the invention from mere mechanical mixtures of precipitated aluminum soaps of saturated fatty acids and precipitated aluminum salts of polyacrylic acid. The present invention is not concerned with mechanical mixtures of individually precipitated alu minum soaps.

The water-soluble soaps of the saturated aliphatic monocarboxylic acids which are used in the production of our novel products are water-soluble compositions produced by alkaline saponification of (l) a saturated fatty acid containing from about 16 to about 22 carbon atoms, (2) a mixture of said fatty acids, (3) a glyceride contain ing as a major constituent thereof saturated fatty acids having a carbon chain length of from 16 to 22 carbon atoms, (4) a mixture of said glycerides or (5) a mixture of said fatty acids with said glycerides. Thus, for ex ample, sodium, potassium or ammonium salts of palmitic acid, stearic acid, arachidic acid or behenic acid or mixtures thereof can be used in the production of the novel products of this invention. Moreover, sodium, potassium or ammonium soaps of the type produced from glycerides containing major quantities of natural mixturesof such acids, as, for example, hydrogenated tallow, hydrogenated soybean oil, hydrogenated cottonseed oil, hydrogenated coconut oil, hydrogenated castor oil, etc. or mixtures thereof can be employed. In addition, water-soluble soaps of the natural mixtures of fatty acids derived from such glycerides or mixtures of water-soluble soaps produced from fatty acids and water-soluble soaps produced from glycerides can be used in producing our novel products.

The water-soluble salts of the polyacrylic acids which are used in producing the multiple aluminum soap com positions of this invention are sodium, potassium and ammonium polyacrylates. The only restriction on the polyacrylic salt employed in producing the products of this invention is that the said salt must be completely soluble in water. Since the novel aluminum soap compositions of this invention are precipitated from aqueous solutions having dissolved therein the fatty acid soaps and the polyacrylate salt, a Water-soluble polyacrylate salt must be used. Thus, irrespective of the molecular weight of the polyacrylic acid portion of the salt molecule or the manner in which either the polyacrylic acid or the water-soluble salt thereof was produced, any watersoluble salt of a polyacrylic acid can be employed in producing the products of this invention. In the preferred embodiment of the invention, a sodium polyacrylate which, as an aqueous solution containing about 15%, by weight, of solids, has a viscosity at a temperature of about 25 C. of from 50,000 centipoises to 100,000 centipoises is employed. The viscosity of the material can be determined conveniently by means of a Brookfield Synchro-lectric viscosimeter, model H.B.F. using H.B.F.'Spindle No. 4 at 5 revolutions per minute.

The ratio of water-soluble salt of the polyacrylic acid to water-soluble salt of the saturated aliphatic monocarboxylic acid which is present in the aqueous solution from which the aluminum soap compositions of the invention are precipitated can be varied to some extent. In its broadest embodiment, the invention contemplates the precipitation of the aluminum soap compositions from an aqueous solution containing the water-soluble salt of the polyacrylic acid in quantities ranging up to about by weight, said weight being based on the weight of the water-soluble soap of the saturated aliphatic monocarboxylic acid present therein. However, the preferred products of the invention are produced from an aqueous solution containing about 5% by weight, based on the weight of the fatty acid soap, of a water-soluble salt of polyacrylic acid. As little as 1.0% by weight, of a watersoluble polyacrylate salt, however, can be employed in conjunction with the water-soluble soap of the saturated aliphatic monocarboxylic acid in producing our products. As a general rule, there is no particular advantage in using less than 1.0% by weight of a water-soluble polyacrylate salt. However, such compositions are fully within the scope of the invention.

The process by which the novel compositions of this invention are prepared is not complicated. An aqueous solution having dissolved therein a water-soluble soap of a saturated fatty acid and an appropriate quantity of a Water-soluble salt of a polyacrylic acid is first prepared. This can be accomplished, if desired, by initially admixing the fatty acid with the polyacrylic acid, subsequently reacting the mixture, at a suitable temperature, with a quantity of alkali suflicient to saponify completely the acids present in the mixture and thereafter diluting the water-soluble products with water to the desired concentration. Any suitable alkali, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, etc. can be employed for this purpose. In an alternate embodiment of the invention, the watersoluble salt ofa saturated aliphatic monocarboxylic acid and the water-soluble salt of a polyacrylic acid can be produced independently of each other, as, for example with an alkali, such as, sodium hydroxide, potassium hydroxide, etc. The water-soluble salts thus produced are thereafter admixed either prior or subsequent to their dissolution in a desired quantity of water. This latter procedure, using sodium hydroxide as the saponifying agent in each instance is employed in producing the preferred products of the invention.

Processes for the conversion of organic acids or glycerides into water-soluble salts or soaps using an alkali are well known in the art. Generally, saponification is accomplished by reacting the salt-or soap-forming material with alkali in the presence of a small quantity of water. Many variations in the basic process are available, however, for accomplishing the desired result. Since water-soluble soaps and salts produced by any of theprior art processes are fully suited for use in pro- 4 ducing the products of this invention, nothing herein should be construed as limiting the invention to the use of compositions produced by any one particular method. In carrying out the conversion of the soap-forming fatty material and the polyacrylic acid to water-soluble soaps and salts thereof a quantity of alkali which is at least stoichiometrically equivalent to the quantity of acid present in the mixture is employed. Generally, to insure complete conversion of the acids to a water-soluble salt form thereof and to facilitate, to some extent, the reaction, a slight excess, as, for example an excess of about 1.0% by weight of alkali, is employed. However, if desired, quantities of alkali greatly in excess of 1.0% excess can be used in producing the water-soluble soaps and salts.

The mixture comprising the water-soluble soap of the soap-forming fatty material and the water-soluble salt of a polyacrylic acid is subsequently diluted with and dis- .solved in water to a concentration of up to about 15% by Weight of solids. In the preferred embodiment of the invention an aqueous solution containing about 5% by weight of the mixture is employed. Generally, the dissolution of the mixture in water can be greatly facilitated by heating the solution. After complete dissolution has been accomplished, the solution is heated to the lowest temperature at which it is free of cloudiness. That temperature will vary depending upon several factors. Among these are the concentration of the soap mixture in the solution and the weight ratio of the water-soluble soap of the soap-forming fatty material to the watersoluble salt of the polyacrylic acid present in the solution. Generally, solutions free of cloudiness will be ob tained at lower temperatures where the concentration of solids in the solution is low and where the solution contains a relatively low ratio of polyacrylate salt to fatty acid soap. The temperature at which the aqueous solution of the mixture is free of cloudiness is the temperature at which the aluminum soap compositions of this invention are precipitated. As a general rule, the solution will be relatively clear and free of cloudiness, and hence the precipitation will be carried out, at a temperature within the range of from about 65 to about C.

The precipitation of the aluminum soap compositions of this invention is accomplished by gradually adding a heated aqueous solution of a water-soluble aluminum salt to the heated aqueous solution containing the water-solu ble fatty acid soap and the water-soluble polyacrylic acid salt. Generally, the aluminum salt precipitant employed for this purpose is aluminum sulfate. However, the invention is not restricted to the use of this particular composition. Any other aluminum salt can be employed provided it is soluble in water at the temperature at which it is to be used and, provided further that it will form water-insoluble aluminum soaps and salts and water-soluble alkali salts with the water-soluble soaps and salts present in the aqueous'solution. In carrying out the precipitation step of the process, the solution of aluminum salt precipitant is added ordinarily to the heated soap solution. If desired, however, this sequence can be reversed. Generally, the solution of the aluminum salt precipitant contains about 20% by weight of water-soluble aluminum salt. However, the concentration of the salt solution employed to accomplish the precipitation has little effect, if any, upon the production of the precipitated aluminum soap composition of the invention or upon the flatting characteristics or the temperature stability properties thereof. Thus, if desired, aqueous solutions containing more or less than 20% by weight of water-soluble aluminum salt can be employed. In the preferred embodiment of the invention, the precipitation step is accomplished by adding an aqueous solution of aluminum sulfate, heated to a temperature of from about 50 C. to about 95 C., to the heated solution containing the water-soluble soap and salt mixture. However, the inven- '5 tion is not to be construed as limited to compositions precipitated at temperatures within that specific range.

The quantity of aluminum salt employed to accomplish the precipitation should be at least sufficient to react with all of the water-soluble soap and salts present in the solution. While the use of a stoichiometrically equivalent quantity of aluminum salt solution should obviate the possibility that any water-soluble soap will-be occluded in the water-insoluble multiple aluminum soap composition, an excess quantity can be, and is, at times, preferably employed.

After the multiple aluminum soap composition has been precipitated, it can be separated from the aqueous solution in which it is dispersed by an convenient means. Generally, this step can be readily accomplished by passing the dispersion through a suitable filter. The filtered prodnot is subsequently washed several times in water to remove residual water-soluble salts present. The washing step is ordinarily carried out in water heated to a temperature of from about 40 C. to about 70 C. After washing, the product is dried, generally in an. oven heated to a temperature of from about 100 F. to 180 F., and, subsequently ground, by appropriate means, to a fine white powder.

As disclosed heretofore, the products of this invention are well suited for use as flatting agents for paint, lacquer and varnish formulations. They are superior to many of the fiatting agents of the prior art in that no thickening or gelling occurs in formulations containing these compositions either at the temperatures developed in grinding them into the vehicle or at the temperatures normally en countered in storing them. In many instances, when used in a paint, varnish or lacquer formulation, the compositions of the invention will produce a far superior flat appearance than many of the flatting agents known and used in the art. However, although our products are useful as fiatting agents in paint and varnish products they are particularly designed for use in the production of lacquers. The manner in which our products are employed as fiatting agents for lacquer will be quite obvious to the art. In general, it has been found that when 3.0% by weight of the products of this invention, based on the Weight of the lacquer, are ground into lacquers excellent results are obtained. However, lesser quantities of these compositions, as for example 1.0% by weight, based on the weight of the lacquer provide equally outstanding results.

Moreover, if desired, the multiple aluminum soap compositions of this invention can be employed in quantities substantially greater than 3% by weight, as, for example, in quantities ranging up to about 25% by weight based on the weight of the lacquers. In such an instance, the highly concentrated and homogeneous mass can be diluted to the desired concentration with an additional quantity of the vehicle prior to its use.

For a fuller understanding of the nature and objects of this invention, reference may be had to the following examples which are given merely as further illustrations of the invention and are not to be construed in a limiting sense. All parts given are parts by weight.

Example 1 Five hundred parts of a commercial stearic acid containing at least 85% of stearic acid, the balance being saturated fatty acids containing 16, 20 and 22 carbon atoms, was charged into a vessel and saponified with 121.5 parts of sodium hydroxide. The sodium soap thus produced was diluted with and dissolved in water to a concentration of about 5% by weight. Thereafter, 33.1 parts of an aqueous solution containing about 15% by weight of sodium polyacrylate was added to and dissolved in the aqueous sodium soap solution. The aqueous sodium polyacrylate solution employed had a viscosity at a temperature of about 25 C. of from 50,000 to 100,000 centipoises. The temperature of the aqueous mixture of sodium soap solution and sodium polyacrylate solution was thereafter 6 adjustedto about C. At that temperature, 370 grams of aluminum sulfate, in the form of a 20% by weight aqueous solution thereof and heated to a temperature'of about 65 C., was added in a slow steady stream to the aqueous mixture. The aqueous mixture was continuously stirred during the addition of the heated aluminum sulfate solution. A multiple aluminum soap composition, dispersed in water, resulted from this step. The aqueous dispersion was stirred for a short period of time after the addition of the aluminum sulfate solution was completed. The aluminum soap was separated from the aqueous dispersion by filtration. It was thereafter washed in water to remove any water-soluble salts present. After washing, the product was dried on trays in an oven at a temperature of about 180 F. and thereafter ground through a laboratory mill of the rotating hammer type using a A; inch screen.

This product was a fine, white powdery material. It was evaluated as a fiatting agent in a lacquer formulation. The lacquer employed was C.M.L. lacquer, a product of the Coating Materials Laboratory, Belleville, New Jersey; This product consists of the following named ingredients in the proportions designated: one-half secondary nitrocellulose parts), maleic resin parts), ethyl acetate (284 parts) ethyl alcohol (54 parts), Troluoil (66 parts), butyl alcohol (70 parts) and butyl acetate (70 parts). Troluoil in the lacquer formulation is a trade mark of Anderson-Prichard Oil Corp., Oklahoma City, Okla., for a petroleum solvent prepared by straight run distillation. In the evaluation, 3% by weight of the product of the example was added to the C.M.L. lacquer in a pebble mill. The pebble mill employed was the conventional laboratory scale apparatus used in such testing. It was manufactured and produced by Paul Abbe, Inc., Little Falls, New Jersey. The pebbles employed were ir-' regularly shaped flint stones having diameters of about one-half inch. The lacquer and the product of this example were ground together in the mill for a'period of three hours. At the end of that period a glass slide was coated with a sample portion of the grind. When the coating was completely dry, the specular gloss (indicative of shininess) was measured using a 60 glossmeter with transformer, an apparatus manufactured for such purpose byHenry A. Gardner Laboratory,.Inc., Bethesda, Maryland. A reading of 30 gloss at 60 angle was obtained; A lacquer similarly ground and tested containing 3.0% by weight of ordinary aluminum stearate had a 40 to 45 gloss at 60 angle. These results show that a lacquer ground with 3.0% by weight of the product of this example produces a film which has a considerably lower specular gloss, and hence is less shiny, than that of a lacquer ground with 3.0% by weight of ordinary aluminum stearate. The lacquer did not gel or tend to gel either during the grinding operation or on storage.

To demonstrate that lacquers containing the product of this example are superior to lacquers containing ordinary aluminum stearate, a sample of each of these lacquers was subjected to a heat stability test. In this test a lacquer having ground therein 3.0% by weight of the product of this example and a lacquer having ground therein 3.0% by weight of aluminum stearate were placed, in covered jars, in an oven heated to F. Each sample was allowed to remain in the heated oven overnight and thereafter removed and cooled to room temperature. The sample containing the product of this example was free flowing and fluid. The sample containing the ordinary aluminum stearate, however, was a gel-like mass. These results demonstrate that, for use as flatting agents in lacquers, the product of the example is far superior to ordinary aluminum stearate.

Example II In this example a product was produced in the same manner as was the product of Example I. However, in this instance 100 parts of the commercial stearic acid were saponified with 18.6 parts of sodium hydroxide. 33.3 parts of aqueous solutioncqntaining of sodium polyaorylate were addedato a 5% aqueous solution of the sodium soap of stearic acid thus-obtained. The aqueous sodiumpolyacrylate solution employed herein had a viscosity at a temperature of about C. of from 50,000 to 100,000 centipoises. The multiple aluminum soap composition Was precipitated by adding 58.5 parts of aluminum sulfate in the form of a 20% aqueous solution to the aqueous solution of sodium salts.

The precipitated product was filtered, washed, dried and ground in the manner described in Example I. The product obtained was a fine white powdery material.

The product of this example was evaluated as a fiatting agentin C.M.L. lacquer, in the manner described in Example I. A coating of lacquerhaving a specular gloss of 40 at 60 angle was obtained. The lacquer did not gel or tend to gel either during the grinding operation or on storage. A lacquer containing 3.0% by weight of the product of the example was subjected to the heatstability test described in Example I. The lacquer did not gel during or after heating overnight at 145 F. A sample of lacquer containing 3.0% by weight of ordinary aluminumstearate gelled under these conditions. These results demonstrate that the product of this example is far more suitable as a flattingagent for lacquers than ordinary aluminum stearate. Thus, while in its flatting characteristics, the product of this example is somewhat comparable to a high grade aluminum stearate, the present product has heat stability characteristics which are vastly superior to those of such an aluminum stearate.

Having described our invention, what we claim is new and desire to secure by Letters Patent is:

1. A multiple aluminum soap composition, the organic acid portion thereof comprising a mixture of a polyacrylic acid and a saturated fatty acid having a carbon chain length of from about 16 to about 22 carbon atoms, said multiple aluminum soap composition having been precipitated by adding an aqueous solution of a water-soluble aluminum salt to an aqueous solution containing a watersoluble soap of said fatty acid and from about 1.0% to about 10% by weight based on the weight of the watersoluble soap of said fatty acid of a water-soluble salt of a polyacrylic acid, the cation thereof being monovalent.

2. The composition of claim 1 wherein said multiple aluminum soap composition is precipitated from an aqueous solution containing from about 1.0% to about 5.0% by weight, based on the weight of the fatty acid soap, of said water-soluble salt of polyacrylic acid, the cation thereof being monovalent.

3. A multiple aluminum soap composition, the organic acid portion thereof comprising a mixture of stearic acid and a polyacrylic acid, said multiple aluminum soap composition having been precipitated by adding an aqueous solution of aluminum sulfate to an aqueous solution containing an alkali metal stearate and from about 1.0% to about 5.0 by weight of said stearate of a Water-soluble alkali metal salt of a polyacrylic acid.

4. The composition of claim 3 wherein the alkali metal stearate is sodium stearate and the water-soluble salt of polyacrylic acid is sodium polyacrylate, said polyacrylate, as a 15% by weight aqueous solution, having a viscosity at a temperature of about 25 C. within the range of from about 50,000 to 100,000 centipoises.

5. A composition comprising a nitrocellulose lacquer and from about 1.0% to about 25% by weight thereof of the product of claim 1.

6. A composition comprising a nitrocellulose lacquer and from about 1.0% to about 25% by weight thereof of the product of claim 2.

7. A composition comprising a nitrocellulose lacquer and from about 1.0% to about 25 by weight thereof of the product of claim 3.

8. A composition comprising a nitrocellulose lacquer and fromabout 1.0% to about 25% by weight thereof of the product of claim 4.

References Cited in the file of this patent UNITED STATES PATENTS 1,976,679 Fikentscher et al Oct. 9, 1934 2,398,350 Atwood et al Apr. 16, 1946 2,702,796 Fine Feb. 22, 1955 2,769,711 Wilson Nov. 6, 1956 OTHER REFERENCES Schildknecht: Vinyl and Related Polymers, pages 87- 90, 301-6, John Wiley (1952). 

1. A MULTIPLE ALUMINUM SOAP COMPOSITION, THE ORGANIC ACID PORTION THEREOF COMPRISING A MIXTURE OF A POLYACRYLIC ACID AND A SATRUATED FATTY ACID HAVING A CARBON CHAIN LENGHT OF FROM ABOUT 16 TO ABOUT 22 CARBON ATOMS, SAID MULTIPLE ALUMINUM SOAP COMPOSITION HAVING BEEN PRECIPITATED BY ADDING AN AQUEOUS SOLUTION OF A WATER-SOLUBLE ALUMINUM SALT TO AN AQUEOUS SOLUTION CONTAINING A WATERSOLUBLE SOAP OF SAID FATTY ACID AND FROM ABOUT 1.0% TO ABOUT 10% BY WEIGHT BASED ON THE WEIGHT OF THE WATERSOLUBLE SOAP OF SAID FATTY ACID OF A WATER-SOLUBLE SALT OF A POLYACRYLIC ACID, THE CATION THEREOF BEING MONOVALENT. 